The present invention relates to an environment recognition system for automatically recognizing an environment or peripheral circumstances, as well as, a mobile mechanism with use thereof, and in particular, it relates to the environment recognition system for recognizing a substance within the peripheral circumstances or environment with using a laser beam therein, as well as, the mobile mechanism with use thereof.
In relation to the conventional art, an example of a range finder or distance measuring system is described, for instance, in Japanese Patent Laying-Open No. 2002-368720 (2002). In the distance measuring method described in this publication, towards a target to be measured the distance therebetween (hereinafter, a distance-measurement target) is emitted a carrier wave, which is code-modulated through a first PN code having a predetermined frequency, and then the carrier wave reflected from the target is received. And, a second PN code is produced, having the same PN code but differing from the first PN code, a little bit, in the frequency thereof. A first burst-like correlation signal is obtained from those first and second PN codes, while a second burst-like correlation signal from the carrier wave and the second PN signal, and the distance to the target is obtained from the phase difference between those and the phase difference between the signals, which are obtained through integration of those first and second burst-like signals.
Other example of such the distance measuring apparatus is described, for example, in Japanese Patent Laying-Open No. 2002-55158 (2002). In the distance measuring apparatus described in this publication, a transmittal signal generator portion generates the PN signal of a predetermined chip length, while a light-emitting portion emits a laser light corresponding to the PN code. A light-receiving portion receives the light reflected from the target thereupon, and after digitalization is found the correlation between the PN code; thereby measuring the distance. In that instance, a direct-current component and low-frequency signals are removed from the received signal, and at the same time the transmittal signal generator portion generates the PN signal from the time when the light-receiving portion starts receiving of the signals until to the time when it starts outputting of stable received signals.
With such the conventional distance measuring system as was mentioned above, the laser must be made scanned, mechanically; therefore, it takes a long time to detect the distance to the distance-measurement target, and also there is a possibility of looking over the distance-measurement target under the condition when the target is moving. Also, under the condition when the distance-measurement target is moving, and furthermore when the distance-measurement target lies within a substance, which is under the condition of movement, there is a possibility that distortion is caused on the configuration of the distance-measurement target detected. For this reason, when the distance-measurement target moves at high velocity, or on the contrary thereto, when the distance measuring system moves at high velocity, it is impossible to grasp or recognize the peripheral circumstances or environment, correctly. Further, the distance measuring apparatus described in those Japanese Patent Laying-Open No. 2002-368720 (2002) and Japanese Patent Laying-Open No. 2002-55158 (2002), for example, there is given the detailed description, in particular, in relation to processing of such the signals measured; however, there is no consideration paid upon a means for dissolving the drawbacks of the conventional arts mentioned above.